Best genral purpose power mosfet.

[David97]

Hi everyone (1st post). I'm looking for a inexpensive power mosfet for testing and for projects. The purpose is to control medium to large loads such as motors. An example is a project I'm working on now, where I need to switch a cars ignition coil on and off using a 555 timer to make a pulse jet igniter. I have also been experimenting using windsheild wiper motors for robots, and need a suitable fet to do this. I know I haven't given much info, but I just need something in my parts draw for these types of applications.

Looking to make a bulk order of both N-channel and the P-channel equivalent.

Thanks for any help.

[TerminalJack505]

I'd vote for IRF530 and IRF9530.

Edit: Said IRF930 but meant IRF530.

[kingofkya]

I like to have to have a selection:)

I have been useing these guys for common parts lately:
http://www.taydaelectronics.com/

There is quite a few cheap ones to get you started you may want to do a search on whatever you order to make sure its not a discontinued model though.

[David Hess]

Hi everyone (1st post). I'm looking for a inexpensive power mosfet for testing and for projects. The purpose is to control medium to large loads such as motors. An example is a project I'm working on now, where I need to switch a cars ignition coil on and off using a 555 timer to make a pulse jet igniter. I have also been experimenting using windsheild wiper motors for robots, and need a suitable fet to do this. I know I haven't given much info, but I just need something in my parts draw for these types of applications.

Driving an ignition coil and switching a motor are different enough that I would want to use different parts or at least different switching circuits.  An ignition coil in particular is a good place for a MOSFET to drive a bipolar cascode switch although in that case the MOSFETs could be similar.

Looking to make a bulk order of both N-channel and the P-channel equivalent.

MOSFETs do not have complementary pairs to the extent that bipolar transistors do.  For a given voltage and die size which determines the wattage and gate charge, the P-channel MOSFET will have a significantly higher drain to source resistance and lower current rating.  For equal drain to source resistance, voltage, and current ratings, the N-Channel MOSFET will have a smaller die size yielding lower wattage and lower gate charge.

So for linear applications I pick MOSFET complementary pairs by matching their power rating as a proxy for die size.  In switching applications where rated power dissipation is usually irrelevant, I pick them based on voltage and current.

As far as finding a low cost generic part, I would just search Mouser or Digi-Key or similar for P-Channel devices in TO-220 packages and sort by price and then look for the N-Channel part matched by power for analog and current for switching.

[David97]

Thanks everyone.

[rob77]

i like the hexfets from IR.
IRFZ34N N-chan + IRF9Z34N P-chan

the IRFZ34N has a relatively low gate capacitance - approx. 700pF , so it's easier to drive them with "weak" outputs.

[retrolefty]

"logic level" power mosfets are nice if you need to interface with TTL digital output voltage.